Method for refining titanium, zirconium, cerium, hafnium and thorium



May 21, 1957 s. T. JAZWINSKI ETAL 2,793,106

METHOD FOR REFINING TITANIUM, ZIRCONIUM, CERIUM, HAFNIUM AND THORIUM Filed June 15, 1954 dzarz 0M, 4%

ATTORNEYS.

METHOD FOR REFINING TITANIUM, ZIRCO- NIUM, CERIUM, HAFNIUM AND THORIUM Stanislaw Teodor liazwinski, Camp Hill, Pa., and Joseph A. Sisto, New York, N. Y., assignors to Barium Steel Corporation, New York, N. Y.

Application June 15, 1954, Serial No. 436,842

Claims. (Cl. 75-.5)

This application relates to the refinement of metals and it relates more particularly to the increase in the purity of such metals as titanium zirconium, cerium, hafnium and thorium.

This invention has application not only to the refinement of titanium, zirconium, cerium, hafnium and thorium produced as by the metallurgical process described in our copending application, Serial No. 436,841, filed June 15, 1954 and entitled, Method for Producing Titanium and the Like, but it has application as well for the refinement of titanium, zirconium, cerium, hafnium and thorium produced by other metallurgical processes or present in combination with othermetallic components and compounds as impurities thereof or the like.

.t is an object of this invention to produce and to provide a method for producing a highly refined titanium, zirconium, cerium, hafnium or thorium and it is a related object to provide a refining process of the type described which does not make use of excessively high temperatures for metallic reduction, which does not make use of electrolytic methods for separation to produce a relatively pure metal, and which is substantially free of the expensive and laborious systems which have heretofore been employed for production and refinement of the metals of the type described.

More particularly, it is an object of this invention to provide a method for refining titanium, zirconium, cerium, hafnium and thorium which is relatively simple and inexpensive; which does not require expensive equipment nor consume a great deal of additional materials; which produces a product in high yield and in high state of purity; which is capable of being carried out in a continuous operation for mass production, and which requires a relatively small amount of labor and space.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustra tion, but not of limitation, an embodiment of the invention is shown in the accompanying drawing in which Figure l is a schematic view of the arrangement of equipment for carrying out the invention in a continuous flow process.

The theory upon which this invention is based for refinement of the metals resides in the ability to form a compound by electronic excitation in which titanium, zirconium, cerium, hafnium or thorium, when heated to elevated temperature and pressure in the presence of carbon monoxide, causes a regrouping and formation of the compound by molecular association. The compound which forms selectively of the metallic components described, as distinguished from the other materials which may be present therewith, is produced in the form of a liquid under the temperature and pressure conditions existing and while purification of the titanium, zirconium, cerium, hafnium and thorium depends upon the instability of the compound for reconversion by disassociation during electron excitation to release the metallic component from the carbon monoxide, the compound that is formed is sufiiciently stable at boiling temperature 2,793.,l06 Patented May 21, 1957 to enable distillation of the compound for separation from the remainder to enable reconversion to be effected in a separate chamber resulting in the production of a purified titanium or the like.

The compound which appears to be formed by the molecular associaiton of the metallic component with carbon monoxide is believed to have the general formula M(CO)7 in which M is a metal selected from the group consisting of titanium, zirconium, cerium, hafnium and thorium. Use will hereinafte r be made of the formula in reference to the compound that is formed. The compound exists in liquid form under the conditions for electronic excitation. During molecular association it has a vaporization point at higher temperatures at atmospheric pressure and becomes unstable for reconversion by thermal reaction for release of the components of which it is originally formed to separate the metallic component from the remainder. By employing the novel conditions described in a sequence of steps for regrouping to form the compound, removal of the compound from the residue followed by reconversion becomes possible to extract the titanium and the like metallic components from the remainder to produce a purified metal.

Description hereafter will be made to the process for refining titanium in accordance with the practice of this invention. It will be understood that except for slight changes in temperature or pressure or both, zirconium, cerium, hafnium and thorium may be refined under similar conditions.

The titanium to be refined is loaded through an inlet 10 into a pressure vessel 11 having means such as burners 12 for heating the interior of the vessel, an inlet 13 in the lower portion for admitting carbon monoxide and for the admission of other gasses in the event that an inert gas is used in addition to carbon monoxide to maintain the desired pressure in the vessel. The lower end portion of the vessel is formed with a trap door 14 or the like for the removal of residue and an outlet 15 is provided in the upper portion for passage of the vapors from the pressure vessel to a precipitation vessel 16 in communication therewith.

The material 17 which is loaded into the pressure vessel is preferably reduced to a finely divided state, otherwise the time consumed for conversion or molecular association to form the compound M(CO)7 will be ex- 'r tended by the resistance to convert the surface portion of the metallic component before access is available to the underlying portions. If the raw material contains oxygen in gaseous or in a combined form, it is expedient to supply carbon or the like material such as activated car- "1 bon in amounts to take up all of the oxygen and form carbon monoxide. Additional carbon monoxide gas to provide an amount sufiicient to react with the titanium to form Ti(CO)'1 is introduced in the chamber and use is made of additional carbon monoxide or an inert gas,

such as helium, argon and the like, to maintain madeatmospheres pressure is required for carrying out the desired reaction'and to produce a compound which is stable in a liquid state over a fairly wide temperature range. More than 10 atmospheres pressure can be used but the yield is not proportionately increased and the cost in materials andv apparatus required to generate and maintain such pressures becomes excessive and the process becomes more limited with respect to the size of load and equipment that can be employed.

At the preferred pressures of from 48- atmospheres, excellent results have been secured with a temperature of about 400 C. The temperature may be lowered to about 300 C. but the rate of reaction beginsto fall off markedly and higher pressures are required. By the same token, it is undesirable to make use of a temperature in excess of 600-800 C. since this temperature approaches the point of instability of the compound that is formed re gardless ofpressure.

Under the conditions exist ng, the materials are maintained in the pressure vessel under a constant state of agitation by stirrers- 18 until the major portion ofthe titanium has been converted to the liquid complex compoundv During reaction the vessel is, of course, sealed olt for maintaining the desired pressure levels.

Conversion appears to take place rather rapidly. When the amount of available titanium becomes depleted and the reaction rate becomes slow, as evideneed'by'consump-- tion of the carbon monoxide, the pressure is released and the temperature in the vessel is raised to the boiling point for the compound. This is usually 50100 C. above its formation but may be at or slightly below the temperature of formation when pressures in excess of 2 atmospheres have been used in forming the compound. When the boiling temperature is reached, valve 19 is opened to communicate the pressure vessel with the precipitation chamber for bleeding the compound vapors from the first into the latter. When distillation has been completed, the. valve is again closed to seal off the vesselsv onefromthet other. The first vessel is again loadedfor another cycle to form the compound by molecular association while the precipitation chamber is heated to a temperature which may be 50-100 higher than the boiling point for molecular excitation to cause disassociation of the compound which releases carbon monoxide from the metallic. components which precipitate and collect at the bottom of the vessel as fine particles 20 of about atomic dimension.

The precipitation vessel is fitted with a gaseous inlet 21 at the top for introduction of inert gases such as argon and helium and with an outlet 22 to purge the precipitation chamber of the gaseous vapors remaining therein. Ordinarily the purged gases and vapors will be led into one or more additional precipitation chambers for further reaction to disassociate any compound which may remain for more complete recovery. Not infrequently, it is desirable to make use of a cascade arrangement of precipitation chambers, to achieve disassociation of a part of the vapor in each chamber thereby to increase the capacity of the system and to increase the yield of the device and it may be desirable also to associate more than one precipitation chamber with each pressure vessel for supply of vapors therefrom as a feeder and then to lead the waste gases from each precipitation chamber into one or more refining chambers for disassociation of any compound which. remains. V

The precipitation chambers are supplied with means for heating, such as gas burners 24, and the lower end portion is formed with a trap door 23 to gain access to the interior thereof for the removal of titanium which collects on the bottom. Because of the pyrophoric character of the powdered titanium, it becomes necessary to avoid contact with oxygen and, for thispurpose, it is best to maintain an atmosphere of inert gas about the material during discharge and loading.

The steps of refinement may be repeated in the event that still further refinement is required. The product may be used as such in the process of powdered metallurgy or the product may be smelted down into ingots or poured into various shapes. i

Zirconium, cerium, hafnium or thorium may be substituted for titanium in the process described without sub stantial change in the processingsteps except for variation in the pressure and temperature conditions. Usually the temperature will be slightly higher for molecular association and for molecular disassociation and the boiling point of the compound will be higher also with compounds of higher atomic weight. The increase in the temperatures of association, disassociati'on and boiling point will be somewhat proportional to the increase in weight, as may be expected.

The carbon monoxide which is released upon reconversion. or disassociatiorr may be recycled after suitable rectification for reuse in. the. pressure vessel. Thus it will be apparent that the consumption of raw materials in the process described will be maintained at a minimum and that the cost of equipment, labor and fuel will be very low because of the, very large capacity possible with very low lClllPElfltlll'B and pressure.

It will be evident from the description that the process is capable of continuous operation for mass production and. that changes may be made in the details of construction, arrangement and operation of the equipment and in the temperature and pressure conditions for reaction within the; limits described without departing from the spirit of the invention, especially asdefined in the following;claims.- I I What is claimed is:

1. In the, method of refining titanium, zirconium, cerium, hafnium and thorium, the steps of introducing the raw metal in finely divided form into a pressure chamber, introducingcarbon monoxide into the chamber in amounts greater than 7, molecular weights, of carbon monoxide per one atomic eight of the metal, heating the materials in the chamber while under pressure to cause molecular association between the carbon monoxide and the metal to form a complex compound which is stable at the boiling point temperature of the compound but which is unstable at higher temperatures to, cause molecular disassociation.

2. In the method of refining titanium, zirconium, cerium, hafnium and thorium, the steps of introducing the base metal in finely divided form into a pressure chamber, introducing carbon monoxide into the pressure chamber in amounts at least sutficient, to convert the metallic components into a compound having the general formula M(CO) '1 in which M is a, metal selected from the. group consisting of titanium, zirconium, cerium, hafnium and thorium, heating, the materials under pressure to cause cerium; hafnium and. thorium, the. steps of introducing the base metal in finely divided form into a pressure chamber, introducing carbon monoxide into the pressure chamber in amounts, at least sufiicient to convert the metallic component into a compound having the general formula M(CO)7 in which M is a metal selected from the group consisting of titanium, zirconium, cerium, hafnium and thorium, maintaining a pressure within the chamber above 2 atmospheres during the reaction, and heating the materials under pressure to a temperature in excess of 300 C. but below 800 C. to form a. complex compound by molecular association between the carbon monoxide and, the metallic component which is stable at the boiling point of the compound but unstable at higher temperatures to; cause molecular disassociation.

4. In the method of refining titanium, zirconium, cerium, hafniumand thorium, the steps of introducing the base metals in finely divided form. into a pressure chamber, introducing carbon monoxide into the pressure chamber" in amounts at least suiiicient to convert the metallic. components into a compound having the general formula M('CO)7 in which M is a metal selected from the. group consisting of titanium, zirconium, cerium,

hafnium and thorium, maintaining a pressure within the chamber between 2-10 atmospheres during the reaction, and heating the materials under pressure to a temperature in excess of 300 C. but below 800 C. to form a complex compound by molecular association between the carbon monoxide and the metallic component which is stable at the boiling point of the compound but unstable at higher temperatures to cause molecular disassociation.

5. The method as claimed in claim 1 which includes the additional step of adding carbon in finely divided form with the base metal in amounts sufiicient to take up any available oxygen and form carbon monoxide.

6. In the method of refining titanium, zirconium, cerium, hafnium and thorium, the steps of introducing the base metals in finely divided form into a pressure chamber, introducing carbon monoxide into the pressure chamber in amounts at least sufiicient to convert the metallic component into a compound having the general formula M(CO)7 in which M is a metal selected from the group consisting of titanium, zirconium, cerium, hafnium and thorium, heating the materials while under a pressure of at least 2 atmospheres to cause molecular association between the carbon monoxide and the metallic component to form a complex compound which is stable at boiling point temperature and slightly above but which is unstable at higher temperatures to cause molecular disassociation, and heating the product above the boiling point of the compound but below the thermal breakdown temperature to separate the compound from the remainder.

7. in the method of refining titanium, Zirconium, cerium, hafnium and thorium, the steps of introducing the base metals in finely divided form into a pressure chamber, introducing carbon monoxide into the pressure chamher in amounts at least suflicient to convert the metallic component into a compound having the general formula M(CO)7 in which M is a metal selected from the group consisting of titanuim, zirconium, cerium, hafnium and thorium, heating the materials while under a pressure of at least 2 atmospheres to cause molecular association between the carbon monoxide and the metallic component to form a complex compound which is stable at boiling point temperature and slightly above but which is unstable at higher temperatures to cause molecular disassociation, heating the product above the boiling point of the compound but below the thermal break-down temperature to separate the compound from the remainder,

and heating the distillation product to a temperature sufiicient to cause molecular disassociation of the compound to release carbon monoxide as the gas and precipitate the metallic component as a fine powder.

8. in the method of refining titanium, zirconium, cerium, hafnium and thorium, comprising the steps of heating the base metal in finely divided form in the presence of carbon monoxide in amounts suflicient to convert the metallic component to a compound having the general formula M(CO)7 in which M is a metal selected from the group consisting of titanium, zirconium, cerium, hafnium and thorium, maintaining a pressure of at least 2 atmospheres during the reaction, separating the compound from the remainder, and reconverting the compound by thermal breakdown into its components to release carbon monoxide as a gas and to precipitate the metallic component as a fine powder.

9. In the method of refining titanium, zirconium, cerium, hafnium and thorium, in which the metals are present in the form of a compound having the general formula M'(CO)'1 in which M is a metal selected from the group consisting of titanium, zirconium, cerium, hafnium and thorium, the steps of heating the compound to a temperature above the boiling point but below the thermal break-down temperature to distill oh the compound from the remainder, and then reconverting the compound into its molecular components to free the carbon monoxide as a gas and toprecipitate the metallic component as a fine powder;

10. In the method of refining titanium, zirconium, cerium, hafnium and thorium, in which the metals are present in the form of a compound having the general formula M(CO)1 in which M is a metal selected from the group consisting of titanium, zirconium, cerium, hafnium and thorium, the step of heating the compound to a temperature 'sufiicient to cause thermal break-down into its molecular components to release carbon monoxide as a gas and to precipitate the metallic component as a fine powder.

References Cited in the file of this patent UNITED STATES PATENTS 2,041,493 Schlecht et a1. May 19, 1936 FOREIGN PATENTS 367,481 Great Britain Feb. 25, 1932 

1. IN A METHOD OF REFINING TITANIUM, ZIRCONIUM, CERIUM, HAFNIUM AND THORIUM, THE STEPS OF INTRODUCING THE RAW METAL IN FINELY DIVIDED FROM INTO A PRESSURE CHAMBER, INTRODUCING CARBON MONOXIDE INTO THE CHAMBER IN AMOUNTS GREATER THAN 7 MOLECULAR WEIGHTS, OF CARBON MONOXIDE PER ONE ATOMIC WEIGHT OF METAL, HEATING THE MATERIALS IN CHAMBER WHILE UNDER PRESSURE TO CAUSE MOLECULAR ASSSOCIATION BETWEEN THE CARBON MONOXIDE AND THE METAL TO FORM A COMPLEX COMPOUND WHICH IS STABLE AT THE BOILING POINT TEMPERATURE OF THE COMPOUND BUT WHICH IS UNSTABLE AT HIGHER TEMPERATURES TO CAUSE MOLECULAR DISASSOCIATION. 